JPS5817499B2 - Polyamide polyamide powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a suitable method for efficiently producing porous polyamide powder with excellent adsorption performance at low cost.

Polyamide powder has conventionally been known as an adsorbent, and various methods have been proposed for powdering polyamide resin.

The most typical method is to mechanically crush polyamide chips using a ball mill or the like.

However, such mechanical grinding methods have the disadvantage that the grinding process takes a long time and is inefficient due to the high strength of polyamide9.Furthermore, the temperature rises due to the friction of the machine, causing Since it often happens that the powder exceeds the point, the powder that has been ground is fused again and becomes impossible to grind, which is why grinding is carried out while cooling using an appropriate method.
This cannot be said to be an economically advantageous method since cooling equipment and costs are naturally added.

In addition, most of the powders pulverized by such mechanical methods are approximately spherical and non-porous, so even if the average particle size is reduced and the powder is pulverized, the It has a small surface area and poor performance as an adsorbent.9 On the other hand, apart from the mechanical grinding method described above, polyamide can be dissolved in a suitable solvent at high temperature and pressure, and then cooled. A so-called reprecipitation method has also been proposed, in which powder is pulverized by

As the polyamide solvent used in this reprecipitation method, for example, US Pat.
Further, US Pat. No. 3,130,181 describes aqueous solutions of aliphatic and alicyclic ketones, respectively.

However, this method of dissolving polyamide under high temperature and high pressure and reprecipitating it inevitably requires a container that can withstand high pressure, and the manufacturing and maintenance costs and energy costs for raising the temperature are high. However, like the mechanical crushing method described above, it is economically disadvantageous.

As yet another method, JP-A No. 49-32946 proposes a method of producing granular polyamide by dissolving polyamide in an aqueous hydrochloric acid solution and dropping water or an aqueous alkaline solution9. Similarly, a method in which polyamide is dissolved in an acid and then reprecipitated with a dilute acid of the same type is also described in Japanese Patent Publication No. 13520/1983.

However, this method of dissolving polyamide in acids and reprecipitating it causes variations in the particle size of the resulting powder, and also tends to cause depolymerization due to the acid amide bonds in the polyamide being broken. The present inventors have found that it is difficult to obtain a powder with excellent adsorption performance due to drawbacks such as a decrease in the heat resistance of the body and a decrease in the number of acid amide bonds that serve as adsorption seats. In view of the drawbacks of the prior art as mentioned above,
We conducted extensive research to find a more economically advantageous manufacturing method for polyamide powder.

As a result, porous polyamide powder can be obtained efficiently and at low cost by dissolving polyamide in an aliphatic alcohol solution containing chlorides such as calcium, lithium, and zinc, and then adding water while stirring. They investigated this and completed the present invention.

It has been found that, in addition to the advantage that the method of the present invention can produce polyamide powder more economically than the conventional method, it also exhibits unexpected and remarkable effects as described below.

In other words, the polyamide powder obtained by the method of the present invention has porosity that could not be obtained by conventional methods, and electron micrographs show that countless pores are formed on its surface. Confirmed.

This means that the surface area per unit weight is approximately 1,000,000 yen, and the adsorbent has extremely favorable properties.

The method of the present invention will be explained in detail below.

The first feature of the present invention is that an aliphatic alcohol solution having 4 or less carbon atoms containing calcium chloride, lithium chloride, or zinc chloride is used as a solvent for dissolving polyamide.

When such a mixed solvent of chloride and alcohol is used,
Polyamide can be dissolved at room temperature, and no high-temperature, high-pressure equipment is required, unlike in the case of dissolving polyamide in conventionally known organic solvents.

Therefore, the thermal energy required for melting can be significantly reduced.

The mixed solvent can be prepared by dissolving a chloride such as calsilyl chloride in an aliphatic alcohol solution such as methanol, ethanol, P-O/knol, or buknol, but the amount of chloride to be dissolved in the alcohol solution teeth,
5 to 80% by weight (no special mention is made below).

) is a preferable condition in terms of workability and properties of the powder obtained.

A second feature of the present invention is that polyamide is dissolved in the mixed solvent of chloride and alcohol in a weight fraction of 15% or less relative to the solution.

The amount of dissolved polyamide greatly influences the properties of the obtained powder.

That is, if the amount of polyamide to be dissolved is small,
A fine powder is obtained, whereas at an amount close to 15%, the powder obtained takes on a flake-like appearance.

If the dissolved amount of polyamide exceeds 15%, it is not preferable because it becomes very hard and flaky with few pores, and its performance as an adsorbent deteriorates.

The most suitable amount of dissolved polyamide varies depending on the type of polyamide, but is usually in the range of about 5 to 14%.

When such a range is used, powders with various particle sizes can be freely and efficiently produced depending on the amount.

Note that the term "powder" in the present invention does not refer only to powder, but also includes flake.

When the amount of polyamide dissolved is 15% or less as described above, the resulting powder, whether in powder form or flake form, will be porous with many pores,
It was confirmed that excellent adsorption performance could be obtained.

The most preferred polyamides to be applied to the method of the present invention include nylon 6 and nylon 66, but also nylon 4, nylon 8, nylon 11, and nylon 6/6.
6 etc. can also be applied to the same way.

Furthermore, N-substituted nylons, such as N-methyl nylon and N-isopropyl nylon, can also be applied in the same way. In particular, N-methyl nylon can be used in the present invention because it is possible to obtain a powder with excellent adsorption power. This is a preferred embodiment.

As described above, the method of the present invention is to prepare an aliphatic alcohol solution in which a chloride such as calcium chloride is dissolved in a weight fraction of 15% or less, but various methods can be used for this dissolution method. Needless to say, it can be done.

That is, in addition to the method of dissolving the polyamide in the alcohol solution in one step so that the concentration is 15 or less, after dissolving 15% or more of the polyamide in advance, for example, 18,
An alcohol solution containing chloride in which polyamide is not dissolved or only alcohol is added to this, and 2
There is no problem in adopting a method in which the amount of polyamide dissolved in the final stage treatment is 15% or less.

When water is added to an aliphatic alcohol solution in which a predetermined amount of the polyamide thus prepared is dissolved, while stirring,
Polyamide re-precipitates.

The reprecipitated polyamide is separated in a furnace and thoroughly washed with water to obtain the porous polyamide powder of the present invention.

The polyamide powder of the present invention thus obtained is
It possesses porosity with countless pores on its surface, which could not be obtained with conventional methods, and its performance as an adsorbent is extremely excellent.

In the present invention, the reason why the polyamide powder produced exhibits porosity has not yet been fully elucidated, but
Presumably, chlorides such as calcium chloride used in the present invention are arranged in the -CONH- groups of the polyamide when dissolved, and when water is added and precipitated, the chlorides become encapsulated in the polyamide precipitate, and the subsequent water washing step It is presumed that when the coordinated chloride dissolves into water, it creates pores.

Such a unique effect of the present invention was not observed in conventional dissolution-reprecipitation, and was an unexpected result.

The most useful use of the polyamide powder of the present invention as an adsorbent is the adsorption and removal of polyphenols in vegetable beverages.

In other words, if polyphenols are present in excess in plant-based beverages such as beer, wine, and fruit juice, they will exhibit unfavorable quality phenomena such as turbidity and browning.
In the beverage manufacturing industry, the development of adsorbents for selectively adsorbing and removing polyphenols is being actively conducted.

The polyamide powder of the present invention has the ability to selectively adsorb polyphenols in particular, and is suitably used as the above-mentioned adsorbent.

In order to remove polyphenols, the polyamide powder obtained by the method of the present invention can be used in the manufacturing process of these beverages, for example, by shaping the polyamide powder obtained by the method of the present invention into a cylindrical shape. Either the polyamide powder obtained by the method of the present invention is poured into the intermediate process of these beverages, and after stirring, There are methods such as filtering the polyamide powder through paper, oven cloth, etc. and separating the polyamide powder.

However, the method is not necessarily limited to these methods, and the polyamide powder obtained by the method of the present invention may be brought into contact with these beverages in some form.

Beverages made from plants treated by these methods no longer have quality defects such as astringency, bitterness, browning, etc. Furthermore, the polyamide powder obtained by the method of the present invention In addition to the above uses, it can also be applied to cigarette filters, in which case polyphenols, nicotine, and tar-like substances in cigarette smoke can be removed.

The present invention will be explained in more detail with reference to Examples.

Example 1 300f of calcium chloride was dissolved in 700P of methanol, and 100g of nylon 6 pellets were put into this solution and dissolved while stirring at room temperature for 20 minutes.

To this solution, 3 parts and 7 parts of methanol were poured, and while stirring well, 6 kg of water was gradually added to the solution over a period of 10 minutes.

As water was added, nylon 6 powder gradually precipitated into the liquid.

This nylon 6 powder was filtered through a Buchner PTO and heated to 45°C.
The mixture was washed with 3 tons of warm water and dried in a hot air dryer at 60°C for 2 hours to obtain a nylon 6 adsorbent.

As a separate comparison, the same nylon 6 pellets were mechanically pulverized in a ball mill to obtain pellets that could pass a 200-mesh grain.

12 of each of these were added to 100 cc of commercially available beer, stirred at 2° C. for 5 minutes, nylon 6 was removed by furnace, and the total amount of polyphenols in the P solution beer was measured by the Harris method.

The results are shown in Table 1. From the results in Table 1, it can be seen that the adsorbent prepared by the method of the present invention has an excellent ability to adsorb all polyphenols. Chip 807 was added and dissolved while stirring at room temperature.

Next, 4 tons of water was gradually added to this solution while stirring over a period of 15 minutes to obtain a precipitate of nylon 66 adsorbent.

(This material was washed with water and dried in the same manner as in Example 1 to obtain a nylon 66 adsorbent.

) Separately, as a comparison, the same nylon 66 chips were dissolved in 4 to 9 parts of 6N hydrochloric acid, and 5 tons of water was gradually added thereto to obtain nylon 66 powder.

This material was filtered using a Buchner Okito, washed with water, and then dried under reduced pressure.

Both of these were added to 100 cc of an aqueous solution of 1100 ppp of D-kakiten, which is a type of polyphenol, for 11 hours.
The stirring layer was stirred for a minute, and the nylon 66 was separated from door to door, and the amount of D-kakiten remaining in the furnace solution was determined from ultraviolet absorption.

The results are shown in Table 2. As is clear from Table 2, the nylon 66 adsorbent prepared by the method of the present invention has an excellent adsorption amount of D-catechin.

Example 3 Zinc chloride 5001 was dissolved in methanol 5007, and N-methyl nylon 66 (degree of methylation 10%) 15
Dissolve oy and pour 7 into methanol 29 into this solution,
While stirring, 4.3 tons of water was gradually added until the pouring was completed in 20 minutes, to obtain a precipitate of N-methylnylon 66.

Next, the precipitate of N-methyl nylon 66 was filtered through a Buchner PTO, washed with warm water at 45°C, and before drying.
Transfer to a beaker and dilute with N-methyl nylon 66.

of water was added.

Next, this water-containing N-methyl nylon 66 was poured into water containing 501 and 201 and dispersed using a homomixer. Bleached sulfite pulp 701 made from softwood was added to this dispersion and continued dispersion using a homomixer, followed by testing. A sheet of size 20 Crn x 25 Crr1 of ``L'' and P paper was made into a manual paper machine.

This sheet was dried in a hot air dryer at 103° C. for 3 hours to obtain a sheet containing the adsorbent.

This sheet was cut into a 45-mm circular shape, loaded into a small P filter machine, and treated with 1100 pp of catechol, a type of polyphenol.
An aqueous solution of 1 (l) was flowed at a flow rate of 80,017 m2.hr.

The amount of catechol in this effluent was determined by ultraviolet absorption and was found to have decreased to 21 ppm.

Example 4 Lithium chloride 2007 was dissolved in n-propatool 8001, and 101 nylon 6 chips were added to this solution and dissolved at room temperature.

While stirring this solution, 3 tons of water was gradually added to the solution over a period of 15 minutes to obtain a precipitate of 60%.

This nylon 6 precipitate was filtered through a Buchner PTO and heated at 40°C.
The mixture was washed with 2 tt of warm water and dried in a hot air dryer at 65° C. for 2 hours to obtain a nylon 6 adsorbent.

As a separate comparison, the same nylon 6 chips were mechanically ground in a ball mill to obtain chips with a diameter of 250 mesh.

Pour 0.51 of both into 100cc of commercially available beer,
The mixture was stirred at 3° C. for 5 minutes, nylon 6 was distributed from door to door, and the amount of anthocyanogen, which is a type of polyphenol, in the p-liquid beer was measured using a hydrochloric acid extraction method.

The results are shown in Table 3. As is clear from Table 3,
The adsorbent prepared by the method of the present invention has superior anthocyanogen adsorption ability.

Claims (1)

[Claims] 1. Dissolving polyamide in an aliphatic alcohol solution having 4 or less carbon atoms containing calcium chloride, lithium chloride, or zinc chloride in an amount of 15% or less by weight of the solution, and adding water while stirring. A method for producing a porous polyamide powder characterized by: